Electric train control



' May 8, 1928.

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1;669,377 H. LUND ET AL ELECTRIC TRAIN CONTROL Filed Nov. 22. 1926 2 Sheets-Sheet 1 F'Lgl.

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by wa Their Attorney.

May s, 1928. 1,669,377

H. LUND ET AL I ELECTRIC TRAIN CONTROL Filed Nov. 22. 1926 2 Sheets-Sheet 2 hfiventors: Hans Lund, Hans Laub.

"Meir" Attorney.

Patented May 8, 1928. a

UNITED STATES 1,669,377 PATENT OFFICE.

HANS LUND, OF BERLIN-SCHONEBERG, AND HANS LAUB, 0F BERLIN-TEGEL, GER- MANY, .ASSIGNORS TO YORK.

GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW ELECTRIC; TRAIN common Application filed November 22, 1926, Serial No. 149,997, and in Germany October 31, 1925.

Our invention refers to electric train control and more especially to impror- 'ements in controlling systems of the kind in which two oscillatory circuits are provided, one near the track and the other one on the train. It is an object of our invention to provide means whereby the electric control of trains according to this system! is rendered more reliable and capable of wider application than has hitherto been possible. i

In train controlling systems asv hitherto suggested, in which a. secondary oscillatory circuit is provided on or near the track, while the primary circuit is arranged on the train moving on this track, the current flow.- ing in the secondary circuit will be influenced by the'primary circuit moving past it. in such manner that prcdetern'iined signalling connections are established or sievered. as the case may be. However, a system involving these features has not yet been put to a practiail use for the reason that it is not sufficiently reliable in practical operation. and voltages are used, the condensers insorted in the primary oscillatory circuit, being permanently under full load, are liable to cause disturbances to arise. Apart therefrom, owing to the fact that a primary and a secondary oscillatory circuit are provided, the known switching means become so highly sensitive that even at very small vari ations of frequency on the primary side the tuning relation between thetwo circuits is changed. in such manner that the energy in the primary circuit, when moving past the secondary circuit, will not be changedto a sufficient degree.

These drawbacks are obviated according to the present invention by altogether dispensing with an oscillatory circuit and with condensers in the primary system, merely a coreless coil being provided, which is supplied with current by a source of high frequency current, for instance a high fre quency generator. The secondary circuit whichis mounted upon the track comprises a coil which is positioned to be in inductive relation with the above mentioned coreless coil as the train passes over the track. This coil is connected in circuit with a condenser and switching means the latter of which is adapted to be operated in accordance with desired signals thereby to vary the current More especially, if higher currents Referring first to Figsal and 2,0 is a hi gh frequencygenerator, 7) is a relay and 0' is a coil, all three being inserted in the same circuit, which is the primary circuit disposed on thetrain in motion. The other parts of the system,.which are arrangedon or near the track, comprise a coil (5, a condenser c 'and a switch f, thislatter being, however,

replaceable by a switch 9 adapted to shortcircu t the coil. at, such switch being indicated inthe drawings by dash lines. The control of the switch f or 9 can be made dependent upon the position of a signal on the track.

The operation of this arrangement is illustrated in Fig. 2 where the intensity of the current 'J flowing in the primary circuit is plotted. as ordinates and the speed of the generator, which of course corresponds to the frequency ofthe current, in revolutions per minute, is plotted as abscissa. The curve 7c, represents the current flowing in the primary circuit when the secondary circuit is open and is a slightly ascending straight line. The curve It, represents the current flowing in the primary circuit when the secondary circuit is closed and shows the dependence of the primary current on frequency under this condition. In a practical test the primary circuit was so adjusted that.

with the high frequency generator running at 800 revolutions per minute, a current of 1 ampere flowed in the prin iary circuit. The relay 6 was so chosen that it was not actuated by this current. Vhenever the train travelled past the closed secondary circuit, the intensity of the primary current; at tained about 8.5 amperes or about 8.5 times its original value thereby operating the relay b and causing the desired connections conventially shown at m to be established. The steep curve 75 can be flattened by the insertion of a resistance.

In cases where the frequency of theprimary circuit varies considerably or where great variations of current are desired We have found it preferable to provide a plurality of secondary oscillatory circuits. A combination of this latter type is illustrated in Fig. 2' where the primary circuit resem- "il s he oneshown in Fig. l, but further nice 10 serving; for flattenirequency characteristic of e secondary circuit may for of three oscillatory circuits, is i :e d 5 (5,, and 6,, c a closed by switches 7' f f KQS"QUi'lYQl}', three witches being mechanically connected i each other The operation of an arrangement of this latter type en'iploying two secondary oscillatory circuits is illustrated in Fig. l in which the curve 7.2, represents the current flowing in the primary circuit wnen both secondary circuits are open and the curve 70 represents the primary current when both of the secondary circuits are closed. In a practical test the primary current intensity at 1100 revolutions per minute of the high frequency generator was equal to 0.75 aniperes. The closing of the secondary circuits caused it to rise to 1.6 amperes. The test showed that it the number of revolutions of the generator dropped down to 1M0 or rose up to 1180 per minute, the. primary current was still about 1.5 amperes therebydemonstrating the reliable operation of the system under these varying conditions.

The switches f in the secondary circuits a cap in may be interconnected with the track signals by any convenient means n shown in the drawing and may thereby be arranged to be controlled in accordance with traffic conditions.

Vi e wish it to be understood that we do not 1,eee,377

desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

e claim 1. In a train signaling system, a nonoseiilatory primary circuit mounted upon a train and adapted to be supplied with alternating current, said circuit including an indnctancman indicating device connected in said primary circuit and adapted to respond to currents flowing therein, a'plurality of secondary circuits mounted upon the track each of said secondary circuits being positioned to be simultaneously in inductive relation with said primary circuit and adapted to vary the current flowing therein when said train passes over the track, and a switch in each of said secondary circuits adapted to be operated in accordance with the desired signals.

2. In a train signaling system, a primary circuit mounted upon a train and adapted to be supplied with alternating current, said circuit including an inductance, an indicating device adapted to respond to currents flowing in said primary circuit, a plurality ot' secondary oscillatory circuits mounted upon the track, each of said secondary circuits being positioned to be sinniltancously in inductive relation with said primary circuit andadapted to vary the current flowing therein when said train passes over the track and switches in said oscillatory circuits adapted to be operated in accordance with the desired signals.

in testimony whereof we our signatures.

HANS LUND. HANS LAUB. 

